A schematic of the setup is shown on fig. REF .
It enables standard single-tone microwave optomechanical measurements [1]}, with the additional ability to artificially tune the microwave cavity effective temperature (or population in the quantum language) thanks to a Noise Generator (NG).
This NG is made of two High Electron Mobility Transistor amplifiers (HEMTs) in series (total gain \(64 \ \mathrm {dB}\) ) connected on one side to a 50\(~\) Ohm load, and on the other to a \(4-8 \ \mathrm {GHz}\)  filter [2]}.
At the frequency of the cavity \(\omega _c\) , the applied microwave noise spectrum is essentially flat, with an amplitude \(E_{noise}\)  that can be quantitatively expressed in terms of photon number \(E_{noise}/\hbar \omega _c\) .
The noise level is tuned by inserting fixed attenuators, which lead to an uncertainty (from screwing/unscrewing) of about \(\pm 1 \ \mathrm {dB}\)  in noise level.
